1. Field of the Invention
The present invention relates to high speed data communication (e.g., 1 G-bit/second or higher). In particular, the present invention relates to a signaling technique that reduces electromagnetic interference (EMI) associated with parallel data.
2. Discussion of the Related Art
Parallel data provided at a high data rate transitioning at a fixed frequency (i.e., at fixed regular data intervals) may generate electromagnetic noise with sufficient energy to interfere with operations in other electronic devices (e.g., wireless or cellular telephones). Such electromagnetic noise is characterized by having a large amount of energy concentrated at the frequencies of the data transitions. It is known that a spread spectrum technique can be applied to alleviate the interference by distributing the energy of the electromagnetic noise over a wider range of frequencies.
Significant EMI problems may arise in a deserializer application in which data in a serial data signal are converted to parallel data. Spread spectrum techniques may be applied to reduce EMI. However, to apply spread spectrum techniques to such an application requires an additional external spread spectrum crystal source, a complicated phase-locked loop (PLL) for the receiving the input serial signal and a digital spread spectrum clock generator to modulate the serial data. These additional components increase both the cost and design time for the deserializer circuit.